Functional Status Score for the Intensive Care Unit

Last Updated

September 12, 2022

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Purpose

The Functional Status Score for the Intensive Care Unit (FSS-ICU) is a 5-item performance-based measure that utilizes an 8 point, ordinal scale to measure physical function for patients in the intensive care unit setting. The FSS-ICU examines the patient’s ability to perform the following five tasks: rolling, transfer from supine to sit, sitting at the edge of bed, transfer from sit to stand, and walking. Additionally, there is a baseline version of the FSS-ICU that can be performed retrospectively via phone by proxy.

Link to Instrument

Instrument Details

Acronym FSS-ICU

Area of Assessment

Functional Mobility

Assessment Type

Performance Measure

Administration Mode

Paper & Pencil

Cost

Free

Actual Cost

$0.00

Mixed Populations

5 items are performed: rolling, transfer from supine to sit, sitting at the edge of bed, transfer from sit to stand, and walking
Each task is evaluated using an eight-point ordinal scale ranging from 0 (unable to perform) to 7 (complete independence)
Item scores are summed
The total score ranges from 0-35, with higher scores indicating better physical functioning.

Number of Items

Scoring Sheet
Pen
Chair

10-30 minutes

Depending on the patient’s functional status; can be incorporated as part of a routine physical therapy session with minimal to no additional time required

Required Training

Reading an Article/Manual

Required Training Description

Written guidelines, frequently asked questions document, pocket card and training video available at https://www.improvelto.com/instruments/ (free registration required to access)

Adults

18 - 64

years

Elderly Adults

years

Instrument Reviewers

Heather Littier PT, DPT, MS; Stephanie Hiser PT, DPT, CCS; Bronwen Connolly, MSc, PhD, MCSP; and Dale Needham, MD, PhD

ICF Domain

Body Function
Activity

Measurement Domain

Motor

Considerations

•   Developed for use with patients in the intensive care unit
•   May take extra time depending on patient acuity and presentation
•   If ≤2 tasks were not performed, use the average score from the completed items to score the 1 or 2 missing tasks
•   If >2 tasks were not performed, an overall FSS-ICU score cannot be calculated
•   The FSS-ICU should be used to grade the patient’s physical performance only
•   Unless otherwise stated, scoring of the FSS-ICU should be based on only one evaluator physically assisting/supervising the patient.
•   Scoring of the FSS-ICU must be completed without the use of a patient lift device
•   Scoring should be based on what is performed during the session, rather than what the patient is capable of or what has been previously performed

Standard Error of Measurement (SEM)

ICU Patients: (Huang, 2016; n = 819; Mean Age = 70 (SD = 13 years))

SEM for ICU awakening/admission (n = 807): 1.3
SEM for ICU discharge (n = 800): 2.4
SEM for Hospital discharge (n = 91): 1.9

ICU Patients: (Alves, 2019; n = 100; Mean Age = 72 (SD = 16 years))

SEM for ICU discharge (n = 100): 0.54

Minimal Detectable Change (MDC)

ICU patients: (Huang 2016; n = 819)

MDC for ICU awakening/admission (n = 807): 3.1
MDC for ICU discharge (n = 800): 5.4
MDC for hospital discharge (n = 91): 4.5

ICU Patients: (Alves, 2019)

MDC for ICU admission (n = 100): 1.0

ICU Patients: (Richtrmoc, 2020)

MDC for ICU discharge (n =40): 2.9

Minimally Clinically Important Difference (MCID)

ICU Patients: (Huang 2016, n = 819)

MCID for ICU patients estimated at 2.0 - 5.0

ICU Patients: (Thrush 2022, n=2793)

MCID for all ICU patients: 3.9
MCID for stroke patients (n=644): 4.2
MCID for cardiovascular patients (n=642): 1.8
MCID for medical patients (n=554): 4.2

Test/Retest Reliability

General Intensive Care Unit: (Alves et al. 2019; n = 100; Mean Age = 72 (SD = 16 years))

Excellent test-retest reliability: (ICC = 0.99)

Coronary Intensive Care Unit: (Kahraman et al. 2019; n = 50; Mean Age = 69 (SD = 12 years))

Excellent test-retest reliability: (ICC = 0.99)

Medical-Surgical Intensive Care Unit: (González-Seguel et al. 2020; n = 6)

Excellent test-retest reliability: (ICC = 0.96)

Medical Intensive Care Unit: (Do et al. 2021, n = 31)

Excellent test-retest reliability: (ICC = 0.98)

Interrater/Intrarater Reliability

Surgical Intensive Care Unit: (Hiser et al. 2018; n = 27)

Excellent interrater reliability: (ICC = .98)

Medical Intensive Care Unit: (Hiser et al. 2018; n = 34)

Excellent interrater reliability: (ICC = .99)

Neurological Intensive Care Unit: (Hiser et al. 2018; n = 20)

Excellent interrater reliability: (ICC = .98)

General Intensive Care Unit: (Ragavan et al. 2016; n = 26; Mean Age = 54 (SD = 20 years))

Excellent interrater reliability: (ICC = 0.99)

Coronary Intensive Care Unit: (Kahraman et al. 2019; n = 50; Mean Age = 69 (SD = 12 years))

Excellent interrater reliability: (ICC = 0.99)

General Intensive Care Unit: (Silva et al., 2017; n = 30)

Excellent interrater reliability: (ICC = 0.88)

General Intensive Care Unit: (Alves et al. 2019; n = 100; Mean Age = 72 (SD = 16 years))

Excellent interrater reliability: (ICC = 0.96)

Medical Intensive Care Unit: (Do et al. 2021)

Excellent interrater reliability: (ICC = 0.99)

Internal Consistency

Intensive Care Unit: (Huang et al., 2016; n = 819)

Excellent Cronbach's alpha range:0.78-0.95

General Intensive Care Unit: (Ragavan et al., 2016; n = 26)

Excellent Cronbach's alpha range: 0.99

Coronary Intensive Care Unit: (Kahraman et al. 2019; n = 50)

Excellent: Cronbach’s alpha = 0.95

General Intensive Care Unit: (Alves et al. 2019; n =100)

Excellent: Cronbach’s alpha = 0.95

Medical Intensive Care Unit: (Do et al. 2021)

Excellent: Cronbach's alpha = 0.90

Criterion Validity (Predictive/Concurrent)

Predictive validity:
Intensive Care Unit: (Huang et al., 2016)

For each 1-point increase in FSS-ICU score at ICU discharge, post hospital length of stay decreased by 0.27 days (p < 0.01; n = 136)
For each 1-point increase in FSS-ICU score at ICU discharge, the odds of discharge home increased by 11% (p <0.01; n = 135; ROC analysis C statistic = 0.75; Adequate)

Predictive validity:
Intensive Care Unit: (Tymkew et al., 2020)

A FSS-ICU score at initial assessment of 16 or greater predicted discharge home (sensitivity 71.8%; specificity 73.6%; AUC=0.69; n=1,203)
A FSS-ICU score at ICU discharge of 19 or higher predicted discharge home (sensitivity 82.9%; specificity 73.6%; AUC=0.80; n=1,203)
A FSS-ICU score at hospital discharge of 22 or greater predicted discharge home (sensitivity 84.2%; specificity 79.7%; AUC=0.85; n=1,203)

Construct Validity

Intensive Care Unit:

Convergent Validity:

Prehospitalization: (Huang et al., 2016; n = 78-82)

Adequate validity of the FSS-ICU performed prehospitalization with instrumental activities of daily living (r = 0.55)
Excellent validity of the FSS-ICU performed prehospitalization with activities of daily living (r = 0.80)

ICU Awakening/Admission: (Huang et al., 2016; n = 20-802)

Adequate validity of the FSS-ICU at ICU awakening/admission with activities of daily living (r = 0.39)
Adequate validity of the FSS-ICU at ICU awakening/admission with manual muscle test score (r = 0.44)
Adequate validity of the FSS-ICU at ICU awakening/admission with hand grip % predicted strength (r = 0.40)
Adequate validity of the FSS-ICU at ICU awakening/admission with hand grip strength (r = 0.37)
Adequate validity of the FSS-ICU at ICU awakening/admission with the ICU Mobility Scale (r = 0.46)

ICU Awakening/Admission: (Parry et al., 2015; n = 66)

Excellent validity of the FSS-ICU at ICU awakening/admission with PFIT-s (r = 0.87)
Adequate validity of the FSS-ICU at ICU awakening/admission with MRC-SS (r = 0.69)

ICU Awakening/Admission: (Camus-Molina et al., 2020; n = 30)

Excellent validity of the FSS-ICU at ICU awakening/admission with cumulative inactivity time (accelerometer data) (r = -0.62)
Excellent validity of the FSS-ICU at ICU awakening/admission with MRC-SS (r = 0.67)
Excellent validity of the FSS-ICU at ICU awakening/admission with ICU length of stay (r = -0.70)
Excellent validity of the FSS-ICU at ICU awakening/admission with time on mechanical ventilation (r = -0.60)

ICU Discharge: (Huang et al., 2016; n = 27-800)

Excellent validity of the FSS-ICU at ICU discharge with activities of daily living (r = 0.60)
Excellent validity of the FSS-ICU at ICU discharge with manual muscle test score (r = 0.60)
Adequate validity of the FSS-ICU at ICU discharge with hand grip % predicted strength (r = 0.50)
Adequate validity of the FSS-ICU at ICU discharge with hand grip strength (r = 0.59)
Excellent validity of the FSS-ICU at ICU discharge with the ICU Mobility Scale (r = 0.86)

ICU Discharge: (Parry et al., 2015; n = 66)

Excellent validity of the FSS-ICU at ICU discharge with PFIT-s (r = 0.85)

ICU Discharge: (Alves et al., 2019; n=100)

Excellent validity of the FSS-ICU at ICU discharge with FIM motor domain score (r = 0.94)

During ICU Stay: (Do et al. 2021)

Good validity of the FSS-ICU during ICU stay with Johns Hopkins Highest Level of Mobility Scale (r = 0.63)
Excellent validity of the FSS-ICU during ICU stay with Activity Measure for Post-Acute Care - Basic Mobility Inpatient Short Form (r = 0.90)
Good validity of the FSS-ICU during ICU stay with Medical Research Council sum score (MRC-SS) (r = 0.63)

ICU Discharge: (Camus-Molina et al., 2020; n = 30)

Excellent validity of the FSS-ICU at ICU discharge with cumulative inactivity time (accelerometer data) (r = -0.79)
Excellent validity of the FSS-ICU at ICU discharge with MRC-SS (r = 0.72)
Excellent validity of the FSS-ICU at ICU discharge with ICU length of stay (r = -0.77)
Excellent validity of the FSS-ICU at ICU discharge with time on mechanical ventilation (r = -0.62)

(Dos Reis et al. 2021; n = 122)

Excellent validity of the FSS-ICU at ICU discharge with Early Rehabilitation Barthel Index (r = 0.77)
Excellent validity of hte FSS-ICU at ICU discharge with Barthel Index (r = 0.88)

Hospital Discharge: (Huang et al., 2016; n = 31-91)

Excellent validity of the FSS-ICU at Hospital discharge with activities of daily living (r = 0.80)
Excellent validity of the FSS-ICU at Hospital discharge with manual muscle test score (r = 0.80)
Adequate validity of the FSS-ICU at Hospital discharge with hand grip % predicted strength (r = 0.43) (Huang et al., 2016)
Adequate validity of the FSS-ICU at Hospital discharge with hand grip strength (r = 0.49) (Huang et al., 2016)

Coronary Intensive Care Unit: (Kahraman et al., 2019; n = 50; Mean Age = 69 (SD = 12 years))

Excellent validity of the FSS-ICU at ICU evaluation with handgrip strength (r = 0.76)
Excellent validity of the FSS-ICU at ICU evaluation with knee extension strength (r = 0.70)
Excellent validity of the FSS-ICU at ICU evaluation with the Perme ICU Mobility Score (r = 0.92)
Excellent validity of the FSS-ICU at ICU evaluation with the Katz ADL Score (r = 0.80)

Discriminant Validity (Goal is “Poor” relationship)

Prehospitalization: (Huang et al., 2016; n = 78-82)

Poor relationship between the prehospitalization FSS-ICU with body mass index (r = -0.03)
Poor relationship between the prehospitalization FSS-ICU with continence item from activities of daily living (r = 0.03)

ICU Awakening/Admission: (Huang et al., 2016; n = 20-147)

Poor relationship between the FSS-ICU at ICU awakening/admission with body mass index (r = -0.01)
Adequate relationship between of the FSS-ICU at ICU awakening/admission with continence item from activities of daily living (r = 0.50)

ICU Discharge: (Huang et al., 2016; n = 20-147)

Poor relationship between the FSS-ICU at ICU discharge with body mass index (r = 0.05)
Excellent relationship between the FSS-ICU at ICU discharge with the continence item from activities of daily living score (r = 0.70)
Poor relationship between the FSS-ICU at ICU discharge with hemodialysis status (r = -0.20)
Poor relationship between the FSS-ICU at ICU discharge with steroid use (r = 0.19)
Poor relationship between the FSS-ICU at ICU discharge with insulin use (r = 0.11)

Hospital Discharge: (Huang et al., 2016; n = 31-91)

Poor relationship between the FSS-ICU at hospital discharge with body mass index (r = -0.05)
Adequate relationship between the FSS-ICU at hospital discharge with the continence item from activities of daily living (r = 0.42)
Adequate relationship between the FSS-ICU at hospital discharge with hemodialysis status (r = 0.38)
Poor relationship between the FSS-ICU at hospital discharge with need for home oxygen (r = 0.05)
Poor relationship between the FSS-ICU at hospital discharge with steroid use (r = -0.16)
Poor relationship between the FSS-ICU at hospital discharge with insulin use (r = -0.06)

3^rd Day During ICU stay: (Kahraman et al., 2019; n =50)

Poor relationship between the FSS-ICU at 3^rd day during ICU stay with body mass index (r = -0.07)
Poor relationship between the FSS-ICU at 3^rd day during ICU stay with heart rate (r = -0.24)
Poor relationship between the FSS-ICU at 3^rd day during ICU stay with systolic blood pressure (r = 0.12)
Poor relationship between the FSS-ICU at 3^rd day during ICU stay with diastolic blood pressure (r = 0.21)

Content Validity

No explicit testing done; FSS-ICU was designed by a multi-disciplinary team with expertise in physical functioning assessment in critically ill patients and was modelled on relevant aspects of a physical therapy assessment.

Floor/Ceiling Effects

Intensive Care Unit: (Parry et al., 2015; n = 66; mean age = 58 (SD = 17 years))

Adequate floor effect of 3.0% at ICU awakening
Excellent floor effect of 0% at ICU discharge
Excellent ceiling effect of 0% at ICU awakening
Adequate ceiling effect of 3% at ICU discharge

Intensive Care Unit: (Huang et al., 2016)

Excellent floor effect of 0.5% at ICU admission/awakening, 0.3% at ICU discharge, and 0% at hospital discharge
Excellent to Adequate ceiling effect of 0.7% at ICU admission/awakening, 11% at ICU discharge, and 21% at hospital discharge.

Intensive Care Unit: (Alves et al., 2019)

Excellent floor effect of 0% at ICU admission
Adequate ceiling effect of 16% at ICU admission

Intensive Care Unit: (Camus-Molina et al., 2020)

Excellent floor effect of 0% at ICU awakening
Excellent floor effect of 0% at ICU discharge
Excellent ceiling effect of 0% at ICU awakening
Adequate ceiling effect of 10% at ICU discharge

Intensive Care Unit: (Thrush et al, 2022)

Adequate floor effect of 3.0% at ICU admission
Adequate floor effect of 1.0% at ICU discharge
Adequate ceiling effect of 3.0% at ICU admission
Poor ceiling effect of 23% at ICU discharge

Coronary Intensive Care Unit: (Kahraman et al 2019)

Excellent floor effect of 0% on day 3 of ICU admission
Adequate ceiling effect of 6% on day 3 of ICU admission

Responsiveness

Intensive Care Unit: (Huang et al, 2016) Assessed at baseline (prior to hospitalization; n = 806), ICU admission/awakening (n = 662), ICU discharge (n = 71), and hospital discharge (n = 73)

Statistically significant, positive changes for all time points were found (p <0.01)
Median FSS-ICU score (range: 0 to 35) was 35 prior to admission, 5 at ICU admission/awakening, 20 at ICU discharge, and 29 at hospital discharge.
The effect size was 2.0 from ICU awakening/admission to ICU discharge

Intensive Care Unit: (Richtrmoc et al, 2020) Assessed at ICU admission/awakening (n = 40) and ICU discharge (n = 40)

Statistically significant, positive changes for all time points (p < 0.01)
Median FSS-ICU score was 29 at ICU admission and 33 at ICU discharge
The effect size was 0.52 from ICU admission to ICU discharge

Intensive Care Unit: (Thrush et al, 2022) Assessed at ICU admission (n = 2793)

Effect size for all patients: 0.87
Effect size for stroke patients (n=644): 0.93
Effect size for cardiovascular patients (n=642): 2.60
Effect size for medical patients (n=554): 0.61

Bibliography

Alves G, Martinez B, Lunardi A. Assessment of the measurement properties of the Brazilian version of the Functional Status Score for the ICU and the Functional Independence Measure in critically ill patients in the intensive care unit. Rev Bras Ter Intensiva. 2019;31(4):521-528.

Camus-Molina A, Gonzalez-Seguel F, Castro-Avila A, Leppe J. Construct Validity of the Chilean-Spanish Version of the Functional Status Score for the Intensive Care Unit: A Prospective Observational Study Using Actigraphy in Mechanically Ventilated Patients. Arch Phys Med Rehabil. 2020;101(11):1914-1921. doi: 10.1016/j.apmr.2020.04.019

Do J, Suh G, Won Y, Chang W, Hiser S, Needham D, Chung C. Reliability and validity of the Korean version of the Functional Status Score for the ICU after translation and cross-cultural adaptation. Disability and Rehabilitation. 2021. doi: 10.1080/09638288.2021.1994660

Dos Reis NF, Biscaro R, Figueiredo F, Lunardelli E, Da Silva R. Early rehabilitation index: translation and cross-cultural adaptation to Brazilian Portuguese; and early rehabilitation Barthel Index: validation for use in the intensive care unit. Rev Bras Ter Intensiva. 2021;33(3):353-361. doi: 10.5935/0103-507X.20210051

Dos Reis NF, Figueiredo FCXS, Biscaro RRM, Lunardelli EB, Maurici R. Psychometric Properties of the Barthel Index Used at Intensive Care Unit Discharge. Am J Crit Care. 2022 Jan 1;31(1):65-72. doi: 10.4037/ajcc2022732. PMID: 34972844.

González-Seguel F, Camus-Molina A, Cárcamo M, Hiser S, Needham D, Leppe J. Inter-observer reliability of trained physiotherapists on the Functional Status Score for the Intensive Care Unit Chilean-Spanish version. Physiother Theory Pract. 2020: 1-7. doi: 10.1080/09593985.2020.1753272

González-Seguel F, Camus-Molina A, Leppe J, Hidalgo-Cabalín V, Gutiérrez-Panchana T, Needham D, Guimaráes F. Chilean version of the Functional Status Score for the Intensive Care Unit: a translation and cross-cultural adaptation. Medwave. 2019;19(1):e7439. doi: 10.5867/medwave.2019.01.7439

Gonzalez-Sequel F, Corner EJ, Merino-Osorio C. International Classification of Functioning, Disability, and Health Domains of 60 Physical Functioning Measurement Instruments Using During the Adult Intensive Care Unit Stay: A Scoping Review. Physical Therapy. 2019; 99(5):627-640.

Hiser S, et al. Interrater Reliability of the Functional Status Score for the Intensive Care Unit. JACPT. 2018;9:186-192

Huang, M., Chan, K. S., Zanni, J. M., Parry, S. M., Neto, S., Neto, J. A., … Needham, D. (2016). Functional Status Score for the ICU: An International Clinimetric Analysis of Validity, Responsiveness, and Minimal Important Difference. Critical Care Medicine, 44(12), e1155–e1164.

Kahraman BO, Ozsoy I, Kahraman T, Tanriverdi A, Acar S, Ozpelit E, Akdeniz B, Hiser S, Guimaraes FS, Needham DM, Savci S. Turkish translation, cross-cultural adaptation, and assessment of psychometric properties of the Functional Status Score for the Intensive Care Unit. Disability and Rehabilitation. 2019.
Parry, S. M., Denehy, L., Beach, L. J., Berney, S., Williamson, H. C., & Granger, C. L. (2015). Functional outcomes in ICU–what should we be using?-an observational study. Critical Care, 19(1), 127.

Parry SM, Huang M, Needham D. Evaluating physical functioning in critical care: considerations for clinical practice and research. Critical Care. 2017; 21:249.

Ragavan, V. K., Greenwood, K. C., & Bibi, K. (2016). The Functional Status Score for the Intensive Care Unit Scale: Is It Reliable in the Intensive Care Unit? Can It Be Used to Determine Discharge Placement? Journal of Acute Care Physical Therapy, 7(3).

Richtrmoc M, et al. Effect of early mobilization on respiratory and limb muscle strength and functionality of nonintubated patients in critical care: A feasibility trial. Critical Care Research and Practice. 2020. doi: 10.1155/2020/3526730

Silva, VZMD, et al. Brazilian version of the Functional Status Score for the ICU: translation and cross-cultural adaptation. Rev Bras Ter Intensiva. 2017;29(1):34-38.

Thrush, A., Rozek, M., & Dekerlegand, J. L. (2012). The clinical utility of the functional status score for the intensive care unit (FSS-ICU) at a long-term acute care hospital: a prospective cohort study. Physical therapy, 92(12), 1536-1545.

Thrush A, Steenbergen E. Clinical properties of the 6-clicks and Functional Status Score for the ICU in a hospital in the United Arab Emirates. Arch Phys Med Rehabil. 2022 May 22;S0003-9993(22)00362-8. doi: 10.1016/j.apmr.2022.04.008. Online ahead of print.

Tymkew H, Arroyo C, Schallom M. The use of physical therapy ICU assessments to predict discharge home. Crit Care Med. 2020;48(9): 1312-1318. doi: 10.1097/CCM.0000000000004467

Zanni, J. M., Korupolu, R., Fan, E., Pradhan, P., Janjua, K., Palmer, J. B., … Needham, D. M. (2010). Rehabilitation therapy and outcomes in acute respiratory failure: An observational pilot project. Journal of Critical Care, 25(2), 254–262.